U.S. patent number 7,989,054 [Application Number 12/715,224] was granted by the patent office on 2011-08-02 for digital printing of polymer-coated paper or board.
This patent grant is currently assigned to Stora Enso OYJ. Invention is credited to Jurkka Kuusipalo, Johanna Lahti, Jari Rasanen, Antti Savolainen.
United States Patent |
7,989,054 |
Rasanen , et al. |
August 2, 2011 |
Digital printing of polymer-coated paper or board
Abstract
The invention relates to a method for digitally printing a
polymer-coated paper or board (1), to a paper or board suitable for
the method and to the production of a product package equipped with
digital prints. During digital printing, printing ink particles are
applied in an electric field to the printing surface formed of a
polymer coating at locations corresponding to the print, and the
printing ink is adhered to the printing surface by fusion with the
aid of infrared radiation. In accordance with the invention, the
paper or board (2) to be printed is equipped with an inner coating
layer (3) containing electrically chargeable ethene acrylate
copolymer, such as ethene methyl acrylate copolymer (EMA), and with
a polyolefin-based outer shield layer (4) on top of this, which
contains e.g. low-density polyethene (LDPE) and provides mechanical
strength, forming the printing surface receiving the printing
ink.
Inventors: |
Rasanen; Jari (Imatra,
FI), Lahti; Johanna (Pori, FI), Savolainen;
Antti (Kangasala, FI), Kuusipalo; Jurkka
(Tampere, FI) |
Assignee: |
Stora Enso OYJ (Helsinki,
FI)
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Family
ID: |
32524515 |
Appl.
No.: |
12/715,224 |
Filed: |
March 1, 2010 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20100159215 A1 |
Jun 24, 2010 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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10592640 |
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7695772 |
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PCT/FI2005/000282 |
Jun 16, 2005 |
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Foreign Application Priority Data
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Jun 17, 2004 [FI] |
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20040840 |
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Current U.S.
Class: |
428/195.1;
430/124.1; 428/213; 346/135.1; 428/220; 428/500; 428/332;
428/211.1; 428/337; 428/342; 428/341; 428/537.5; 428/511; 346/141;
428/207; 428/219; 428/512 |
Current CPC
Class: |
G03G
7/0053 (20130101); G03G 7/004 (20130101); Y10T
428/24901 (20150115); Y10T 428/31895 (20150401); Y10T
428/26 (20150115); Y10T 428/31855 (20150401); Y10T
428/31899 (20150401); Y10T 428/277 (20150115); Y10T
428/2495 (20150115); Y10T 428/266 (20150115); Y10T
428/31993 (20150401); Y10T 428/24934 (20150115); Y10T
428/273 (20150115); Y10T 428/24802 (20150115) |
Current International
Class: |
B41M
5/00 (20060101); G03G 7/00 (20060101); B44C
1/17 (20060101) |
Field of
Search: |
;428/195.1,207,211.1,213,219,220,332,337,341,342,500,511,512,537.5
;346/135.1,141 ;430/124.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 466 503 |
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Jan 1992 |
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EP |
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0 629 930 |
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Dec 1994 |
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EP |
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0 729 074 |
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Aug 1996 |
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EP |
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113807 |
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Jun 2003 |
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FI |
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WO 03/054634 |
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Jul 2003 |
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WO |
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Primary Examiner: Shewareged; Betelhem
Attorney, Agent or Firm: Birch, Stewart, Kolasch &
Birch, LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a 37.degree. C.F.R. .sctn.1.53(b)
divisional of, and claims priority to, U.S. application Ser. No.
10/592,640, filed Sep. 13, 2006 now U.S. Pat. No. 7,695,772.
Application Ser. No. 10/592,640 is the national phase under 35
U.S.C. .sctn.371 of International Application No.
PCT/FI2005/000282, filed on Jun. 16, 2005. Priority is also claimed
to Finnish application FI 20040840 filed Jun. 17, 2004. The entire
contents of each of these applications is hereby incorporated by
reference.
Claims
The invention claimed is:
1. A polymer-coated digitally printed paper or board, equipped with
an electrically chargeable inner coating layer containing ethene
acrylate copolymer and with an outer polyolefin-based shield layer
adhered directly to this without any binder to provide mechanical
strength, said outer layer forming the printing surface, and
receiving the printing ink being adhered to the printing surface by
fusion with the aid of infrared radiation.
2. A paper or board as defined in claim 1, wherein the inner
electrically chargeable polymer layer contains ethene methyl
acrylate copolymer (EMA), in which methyl acrylate monomer accounts
for approx. 20 molar %, with a layer weight in the range 7-20
g/m.sup.2.
3. A paper or board as defined in claim 1, wherein the shield layer
consists of low-density polyethene (LDPE), high-density polyethene
(HDPE), or a mixture of these, the layer weight being in the range
2-10 g/m.sup.2.
4. The paper or board as defined in claim 3, wherein the layer
weight is in the range 5-7 g/m.sup.2.
5. A paper or board as defined in claim 1, wherein it is a
packaging board, whose fibre substrate has a weight in the range
130-600 g/m.sup.2.
6. The paper or board as defined in claim 5, wherein the fibre
substrate has a weight in the range 170-300 g/m.sup.2.
7. A paper or board as defined in claim 1, wherein its fibre
substrate has a weight in the range 20-130 g/m.sup.2.
8. A paper or board as defined in claim 7, wherein the fibre
substrate has a weight in the range 40-120 g/m.sup.2.
9. A paper or board as defined in claim 1, wherein infrared
radiation has been used for melting the shield layer with a view to
adhering the printing ink to the printing surface.
10. A paper or board defined in claim 9, wherein polymer-based
printing ink particles are used, which are melted by infrared
radiation so as to adhere to the printing surface.
11. A paper or board method as defined in claim 1, wherein the
inner electrically chargeable coating layer of the paper or board
contains ethene methyl acrylate copolymer (EMA), in which methyl
acrylate monomer accounts for approx. 20 molar %.
12. A paper or board as defined in claim 1, wherein the
electrically chargeable inner coating layer has a weight in the
range 7-20 g/m.sup.2.
13. A paper or board as defined in claim 1, wherein the shield
layer contains low-density polyethene (LDPE), high-density
polyethene (HDPE), or a mixture of these.
14. A paper or board as defined in claim 1, wherein the shield
layer is heat sealable.
15. A paper or board as defined in claim 1, wherein the shield
layer has a weight in the range 2-10 g/m.sup.2.
16. A paper or board as defined in claim 15, wherein the shield
layer has a weight in the range 5-7 g/m.sup.2.
17. A product package equipped with prints, wherein a digitally
printed polymer-coated packaging paper or board as in any one of
preceding claims 1-16 has been creased and heat-sealed to form a
package.
Description
FIELD OF THE INVENTION
The invention relates to a method for digital printing of
polymer-coated paper or board, in which printing ink particles are
applied in an electric field to a printing surface formed of a
polymer coating, corresponding to printing, and the printing ink is
adhered to the printing surface by fusion with the aid of infrared
radiation in order to form a print. The invention also comprises a
paper or board suitable for the method and a method for producing a
product package provided with digital prints.
BACKGROUND OF THE INVENTION
Digital printing as a technique is known and widely used in colour
printing, copying machines and printers, among others. EP Patent
Application 629930 describes digital printing techniques producing
multi-colour print on one or both sides of a moving paper web. The
different printing colour shades are produced at consecutive
synchronised printing stations placed along the web path. Each
station comprises a rotating drum with a charger disposed at its
periphery for generating a regular electric charge on the surface
of the drum. At the drum periphery, the charger is followed by a
print head, such as a laser scanner, which generates a latent image
on the surface of the drum by selective modification of the charge
of the drum surface, the latent image being subsequently developed
at a development station, where printing colour particles charged
with opposite signs are brought to locations on the drum surface
corresponding to the image. After this, the drum surface is
contacted with a paper web guided to pass by laterally in order to
transfer image-forming printing ink particles to the web surface.
To this end, a corona transfer device has been mounted at the
tangential point between the drum and the web, at the opposite side
of the web, the electric current led over the corona transfer
device generating an electric field, which attracts electrically
charged printing ink particles from the drum surface to the paper
web surface. In the immediate vicinity of the corona transfer
device, an alternating current corona device has been mounted to
eliminate the charges of the web, allowing the web to deviate from
the drum surface. The drum surface is then precharged with the
corona device and cleaned from any remaining printing ink
particles, after which the surface is ready for a new printing
cycle, which may equally well be identical with the preceding cycle
as different from this.
As described above, monochrome print can be produced on one side of
a paper at one single printing station using black printing ink. In
multicolour printing, the different printing inks are applied to
the paper at several consecutive printing stations, which operate
with different colours, adding the colours one by one to the print
generated on the moving web. Double-sided printing of a paper can
further be achieved by disposing printing stations as described
above on both sides of a moving paper web.
After a print composed of one or more printing inks has been
applied to the paper as described above, the print is adhered at a
fixing station disposed on the web path. Adhesion takes place by
means of infrared radiators, which heat the web surface, resulting
in fusion of the polymer printing ink particles to the paper.
Eventually, the finished printed web can be either divided into
sheets, which are piled or stitched whenever necessary, or it can
be rewound.
On principle, similar technique is applied in copying machines and
printers, in which the printing substrate consists of individual
sheets instead of a continuous web. Besides paper sheets, plastic
films are suitable as a substrate in copying machines.
WO patent specification 03/054634 discloses digitally printed
papers and boards, whose printing surface consists of a polymer
coating containing electrically chargeable ethene acrylate
copolymer. The specification examined by means of coronation the
chargeability of copolymer of ethene methyl acrylate (EMA),
polyethylene terephtalate (PET) and low-density polyethene (LDPE)
and also conducted a more comprehensive comparative test series
regarding the printing quality obtained in digital printing with
boards coated with different polymers. 20% EMA proved the best
coating polymer, i.e. EMA in which methyl acrylate monomer
accounted for 20 molar %. The results of this specification
indicated a markedly lower digital printing quality of low-density
polyethene (LDPE) and high-density polyethene (HDPE), which are
polyolefins commonly used as the coating of packaging boards.
However, copolymers of ethene acrylate are characterised by being
soft and of having a low fusion point, e.g. the fusion point of 20%
EMA mentioned above is approx. 80-90.degree. C. Due to their
softness, they are exposed to friction and wear when used as the
uppermost coating layer on packaging board. Their low fusion point
makes them readily heat sealable as such, yet excessively
fusionable during sealing, and hence more difficult to control than
e.g. the most commonly used heat-sealing polymer LDPE. Due to their
stickiness, they also cause problems in extrusion, e.g. by their
tendency to adhere to the cooling roll, requiring thus necessarily
the adoption of low running speeds.
WO patent specification 03/054634 mentions the stickiness of EMA,
which increases as the proportion of methyl acrylate monomer in the
polymer increases. The specification has reached an approximate
proportion of 15% of methyl acrylate monomer as a compromise
between non-stickiness of the coating and high printing quality.
The specification also states that it is possible to apply a
protective varnish onto the digitally printed surface after fusion
of the printing ink, however, this would involve a further work
step in the printing process.
SUMMARY OF THE INVENTION
The invention has the purpose of resolving the mechanical problems
mentioned above relating to digitally printed polymer-coated paper
or board so as to achieve a wear-resistant printing surface without
separate protective operations after the printing. The digital
printing method of the invention is characterised by the printing
being performed on paper or board provided with an electrically
chargeable inner coating layer containing ethene acrylate copolymer
and with an upper polyolefin-based protective layer giving
mechanical strength and forming eventually the printing surface
receiving the printing ink.
The invention is based on the surprising observation that high
digital printability achieved with ethene acrylate copolymer does
not disappear or even deteriorate notably when a layer containing
this is coated with a thin polyolefin layer forming a shield layer
acting simultaneously as the printing surface for receiving the
printing ink. The outcome is unexpected, considering that previous
research has found LDPE and HDPE to have poor digital printing
quality.
The invention achieves obvious advantages based on the profitable
mechanical properties of polyolefins, such as LDPE or HDPE. Given
their fusion temperatures higher than those of ethene acrylate
copolymers, they are easier to extrude and coextrude and have
higher wear resistance. They do not markedly affect printing ink
adhesion under IR radiation; they are fusioned with the polymer
component melting under the radiation of the printing ink, perhaps
partly also melting themselves in this conjunction.
Among electrically chargeable ethene acrylate copolymers usable in
the invention, we may cite especially ethene methyl acrylate
copolymer (EMA), in which the proportion of methyl acrylate monomer
is 9-20 molar %, preferably about 20 molar %. Other potential
polymers comprise ethene ethyl acrylate copolymer (EEA), which
closely resembles EMA, and ethene butyl acrylate copolymer (EBA). A
polymer layer containing these polymers has a recommended weight in
the range 7-20 g/m.sup.2.
These polymers can be used as such in the chargeable layer, or they
can be doped in another polymer, such as a polyolefin contained in
an upper shield layer.
Polymers suitable for the outermost coating layer acting as a
mechanical shield and a printing surface comprise, besides the
low-density polyethene (LDPE) and high-density polyethene (HDPE)
mentioned above, their mixtures, or e.g. mixtures in which LDPE is
doped in another polymer, such as e.g. polypropene (PP). LDPE and
its mixtures have the special advantage of easy heat sealability
with commonly used sealers. To ensure good digital printability of
the coating, the shield layer should be thin, preferably with a
weight in the range 2-10 g/m.sup.2 and more advantageously in the
range 5-7 g/m.sup.2.
The method of the invention for producing a product package
provided with prints is characterised by a packaging paper or board
provided with polymer coating layers as described above being
digitally printed in accordance with the invention, and then
creased and heat-sealed to form a package.
The polymer-coated, digitally printable paper or board included in
the scope of the invention is characterised by being provided with
an electrically chargeable inner coating layer containing ethene
acrylate copolymer and with an outer polyolefin-based shield layer
adhered directly to this without a binder in order to provide
mechanical strength, the shield layer forming the printing surface
receiving the printing ink.
When the polymer-coated paper or board of the invention is used
e.g. in food packages, it can be equipped with one or more water
vapour and/or oxygen barrier layers, whose typical polymers
comprise i.a. ethyl vinyl alcohol copolymer (EVOH) and polyamide
(PA). The barrier layer can be disposed between the paper or board
base and the chargeable acrylate copolymer layer, or optionally on
the opposite side relative to the printing surface of the paper or
board. In sealable packages, the paper or board comprises
preferably an outermost, heat-sealable polyolefin layer on both
sides. The polymer layers forming the coating on top of one another
can be produced on the paper or board substrate by coextrusion in a
manner known per se.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is explained in greater detail below by means of
examples and with reference to the accompanying drawing, in
which
FIG. 1 shows a board of the invention having an EMA layer on the
one side and an LDPE shield layer on top of this,
FIG. 2 shows a board of the invention having an EMA layer on the
one side and a HDPE shield layer on top of this,
FIG. 3 shows a board corresponding to the one illustrated in FIG.
1, except that also the opposite side of the board is coated with
an LDPE layer,
FIG. 4 shows a board coated on both sides with an EMA layer and an
LDPE shield layer,
FIGS. 5 and 6 show boards corresponding to the one illustrated in
FIG. 3, but with an EVOH oxygen barrier layer added, and
FIG. 7 shows a board corresponding to the one illustrated in FIG.
3, but with HDPE water vapour barrier layers added on both
sides.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a polymer-coated digitally printable board 1 of the
invention, in which one side of the fibre substrate 2 has been
coated by coextrusion with a polymer coating consisting of an inner
electrically chargeable EMA layer 3 and a thinner outer LDPE shield
layer 4. The fibre substrate 2 may consist e.g. of a triple-layer
board formed of an intermediate layer of chemithermo-mechanical
pulp (CTMP) and outer layers of bleached sulphate, having a weight
in the range 130-600 g/m.sup.2, preferably 170-300 g/m.sup.2. The
EMA contained in the chargeable layer 3 has been formed by
copolymerising ethene and methyl acrylate monomers, with the latter
accounting for 20 molar % in the monomer composition. This EMA
quality has a particularly advantageous digital printing quality.
The EMA layer 3 may have a weight in the range 7-20 g/m.sup.2. The
outer LDPE layer 4 may have a weight in the range 2-10 g/m.sup.2,
preferably 5-7 g/m.sup.2. The LDPE layer 4 acts as the mechanically
durable printing surface of the board, which receives the printing
ink particles and to which the printing ink is adhered by fusion
with the aid of IR radiation. The LDPE layer 4 thus acts as a
shield layer for the underlying softer EMA layer 3, while the
electrically chargeable EMA markedly improves the printing quality
compared to the quality attained with an LDPE coating layer alone.
LDPE in the outer layer 4 has the additional advantage of being
heat sealable and thus apt for various package applications.
The embodiment of the invention illustrated in FIG. 2 differs from
the one in FIG. 1 only in that the polymer of the outer shield
layer 4 is HDPE instead of LDPE. In visual assessments, the polymer
layer combination 3, 4 both of FIGS. 1 and 2 has achieved a high
digital printing quality. Due to its higher fusion point, HDPE is
less readily heat sealable than LDPE, however, applied as a very
thin layer 4 in accordance with the invention, it may melt during
hot-air heat sealing so that tight sealing is provided by means of
the subjacent readily melting EMA layer.
The embodiment of the invention of FIG. 3 differs from the one in
FIG. 1 in that the opposite side of the fibre substrate 2 is
equipped with an LDPE heat-sealing layer having a possible weight
in the range 10-40 g/m.sup.2. Such a packaging board coated on both
sides is particularly suitable for casing and container packages
closed by heat sealing, whose outer surface is provided with
digital prints.
The embodiment of the invention illustrated in FIG. 4 comprises the
EMA and LDPE layers 3, 4 on top of each other as described above,
disposed symmetrically on both sides of the fibre substrate 2. Such
a coated board can be digitally printed on both sides equally well.
If the board is heat sealed to form packages, any one of its two
sides may form the digitally printed outer surface of the
package.
The embodiment of the invention illustrated in FIG. 5 differs from
the one illustrated in FIG. 3 in that an EVOH oxygen barrier layer
6 has been inserted between the fibre substrate 2 and the LDPE
heat-sealing layer 5 on the side of the fibre substrate 2 opposite
to the EMA layer 3. If necessary, a binder layer can be
additionally provided between the EVOH and LDPE layers 6,5. Such a
coated board is suitable for oxygen-proof packages closed by heat
sealing, such as e.g. food packages, in which the outer surface of
the package is digitally printed, with the oxygen barrier 6
remaining within the fibre substrate 2 of the package. The EVOH
layer 6, which prevents both oxygen and water vapour penetration,
may have a weight e.g. in the range 5-10 g/m.sup.2. Instead of
EVOH, the oxygen barrier may also consist e.g. of polyamide. EVOH
and polyamide are also jointly usable as layers on top of each
other, thus mutually complementing the barrier properties of one
another.
The embodiment of the invention illustrated in FIG. 6 differs from
the one shown in FIG. 5 in that the EVOH oxygen barrier layer 6 is
disposed between the fibre substrate 2 and the chargeable EMA layer
3. In FIG. 7, the fibre substrate 2 has also been provided with
HDPE layers 7 acting as water vapour barriers on both sides, these
layers having e.g. a weight in the range 10-20 g/m.sup.2,
preferably with the HDPE layers 7 substantially equally thick. The
latter embodiment is intended especially for packages provided with
digital prints, in which it is desirable to protect the packaged
product and/or fibre substrate 2 against both external moisture and
any moisture caused by the packaged product itself.
Example 1
A series of tests was conducted, in which a cup board with a weight
of 170 g/m.sup.2 was digitally printed and which was coated on one
side with a two-layered polymer coating, the weight of the inner
coating layer being 15 g/m.sup.2 and that of the outer layer 5
g/m.sup.2. A total of 14 boards coated in different ways and
subsequently coronated (samples 1-14) were multi-colour printed
(yellow, blue, red, black) following the technique disclosed by EP
patent specification 629930 at a path speed of 7.35 m/min, and a
six-member evaluation board evaluated the printing quality visually
by ranking the printed samples into order of superiority, in which
the best sample was given the value 1 and the poorest sample the
value 14. The means and deviations have been calculated on these
values. The tests also comprised measurement of the mottling values
of green and red prints and of the abrasion resistance (%) of blue
(cyan) and red (magenta). The results are given in table 1.
Visual evaluation has been considered the chief criterion with
respect to high digital printing quality. However, it has the
drawback of subjective assessments, which appears as value
deviation among the members of the board. Nevertheless, the
distinctly best results of the test series were obtained for
samples 7 and 8, in which the EMA 20 layer (EMA in which methyl
acrylate monomer accounts for 20 molar %) was covered with a thin
LDPE or HDPE layer acting as the printing surface.
Example 2
A test series was conducted comprising digital printing of a cup
board having a weight of 170 g/m.sup.2 and coated on one side with
a two-layered polymer coating, whose inner coating layer had a
weight of 15 g/m.sup.2 and outer layer a weight of g/m.sup.2. A
total of five boards coated in different ways and subsequently
coronated (samples 1-5) were multi-colour printed (yellow, blue,
red, black) following the technique of EP patent specification
629930 at a path speed of 7.35 m/min. The inner coating layer of
samples 3-5 was a polymer mixture containing 5% (sample 3), 15%
(sample 4) or 25% (sample 5) of the polymer used in example 1, EMA
20, i.e. EMA in which the methyl acrylate monomer accounted for 20
molar-%, with the remainder consisting of LDPE. A six-member
evaluation board made a visual assessment of the printing quality
by placing the printed samples in order of superiority, in which
the best sample was given the value 1 and the poorest sample the
value 5. The means of these values were calculated. The results are
shown in table 2.
The by far best result of the test series was obtained with sample
2, in which the material of the innermost layer was pure EMA 20.
Mixtures of EMA 20 and LDPE (samples 3-5) also yielded a better
result than pure LDPE (sample 1).
TABLE-US-00001 TABLE 1 Sample 1 2 3 4 5 6 7 8 Polymer layers Inner
LDPE EMA20 EMA9 HDPE PET EMA20 EMA20 EMA20 Outer LDPE EMA20 LDPE
HDPE PET PET LDPE HDPE Rating Evaluator 1 3 11 6 4 5 14 2 1 2 5 12
3 4 6 14 2 1 3 3 10 5 4 8 14 1 2 4 6 8 4 2 5 14 3 1 5 4 13 3 5 8 14
2 1 6 3 10 7 4 6 14 1 2 Mean 4 10.7 4.7 3.8 6.3 14 1.8 1.3
Deviation 1.3 1.8 1.6 1.0 1.4 0 0.8 0.5 Mottling Green Mean 7.16
5.10 5.72 5.67 6.21 5.23 5.20 5.51 (cyan + yellow) Deviation 0.34
0.26 0.61 0.55 0.11 0.24 0.40 0.31 Red Mean 3.12 3.08 3.37 2.10
3.21 3.51 3.44 3.26 (Magenta + yellow) Deviation 0.21 0.27 0.47
0.17 0.39 0.42 0.52 0.50 Abrasional Cyan 1.9 2.0 0.7 1.6 2.9 1.1
1.8 1.0 resistance % Magenta 6.0 12.4 7.4 6.6 7.2 7.5 11.1 2.8
Sample 9 10 11 12 13 14 Polymer layers SURLYN SURLYN SURLYN EMA9
EMA9 EMA9 LDPE SURLYN PET EMA9 PET HDPE Rating Evaluator 1 8 12 9
13 7 10 2 7 10 13 9 8 11 3 6 7 13 11 12 9 4 10 11 13 9 12 7 5 7 10
11 12 9 6 6 5 11 9 13 12 8 Mean 7.2 10.2 11.3 11.2 10 8.5 Deviation
1.7 1.9 2.2 2.3 2.5 1.9 Mottling Green 5.93 8.25 7.86 6.29 5.49
6.12 (cyan + yellow) 0.52 0.77 0.63 0.38 0.30 0.46 Red 3.81 5.10
3.01 3.38 4.27 5.91 (Magenta + yellow) 0.29 1.01 0.10 0.31 0.65
0.96 Abrasional 2.6 0.8 2.0 5.0 1.5 2.0 resistance % 6.2 6.0 6.1
11.3 8.3 6.0
TABLE-US-00002 TABLE 2 Sample no. 1 2 3 4 5 Polymer layer Rating
Inner LDPE EMA20 5% EMA20 15% EMA20 25% EMA20 Evaluator Outer LDPE
LDPE LDPE LDPE LDPE 1 5 1 2 4 3 2 4 1 2 5 3 3 5 1 2 3 4 4 5 1 3 2 4
5 5 2 1 4 3 6 5 1 2 3 4 Mean 4.8 1.2 2 3.5 3.5
* * * * *